A promising perovskite primary explosive

A primary explosive is an ideal chemical substance for performing ignition in military and commercial applications. For over 150 years, nearly all of the developed primary explosives have suffered from various issues, such as troublesome syntheses, high toxicity, poor stability or/and weak ignition performance. Now we report an interesting example of a primary explosive with double perovskite framework, {(C6H14N2)2[Na(NH4)(IO4)6]}n (DPPE-1), which was synthesized using a simple green one-pot method in an aqueous solution at room temperature. DPPE-1 is free of heavy metals, toxic organic components, and doesn’t involve any explosive precursors. It exhibits good stability towards air, moisture, sunlight, and heat and has acceptable mechanical sensitivities. It affords ignition performance on par with the most powerful primary explosives reported to date. DPPE-1 promises to meet the challenges existing with current primary explosives, and this work could trigger more extensive applications of perovskite.

1.The studied compound (perovskite) is already well established and this is not the first time reported in the literature.Too much emphasis on this is not a good idea.
2. I want the authors to compare the performance of the present compound with some other Azide such as NH4N3, AgN3, CuN6 etc.This will be very much useful for the readers.The authors should also consider Potassium 1,1′-dinitroamino-5,5′-bistetrazolate (K2DNABT)for comparison.Please see the following paper {J.Chem.Phys.143, 064508 (2015)}.I suggest the authors to include the above paper in the introduction part.
3. I would like to know the role of Halogen towards the energetic properties in this compound?4. The Halogens are toxic and I would like to know how the present compound will satisfy the green energetic materials creteria.5. Can this compound be a perfect replacement for PbN6 if so how superior it is when compared to K2DNABT.I want the authors to compare the same.Also K2BDAF should also be compared.
As of now the comparison is not adequate for the energetic properties and I suggest the authors to revise the manuscript accordingly.Also the Hydrogen bonding part should be well discussed.The authors just present without much of discussion.
I would like to review the paper again.

Response to Reviewer #1
Response: We do not agree with your statement for the following reasons.(1) The structure we report is new in the field of energetic materials.Based on our knowledge, many perovskite-based energetic materials have been reported so far, but they show single-perovskite structure, while double-perovskite energetic materials have not been reported.Therefore, your statement of "DPPE-1...... is too similar to the materials already reported" is incorrect.We don't believe that it is necessary to explain this further; (2) Has the energetic perovskite based on component IO4 -been widely studied?According to the related literature (Energetic Materials Frontiers, 2020, 1, 123-135; Inorg.Chem., 2022, 61, 4143-4149; Sci China Mater., 2023, 66, 1641-1648), only one paper has reported the perovskite energetic material based on IO4 -, and it is a single perovskite material used as a biocidal agent (Sci China Mater., 2023, 66, 1641-1648).The so-called "The use of XO4as the main component to construct energetic perovskites has been extensively studied" is not the case.(3) Isn't (H2DABCO)2[Na(NH4)(IO4)6] reported in our manuscript a double-perovskite energetic material?In the published papers, some ABX3-type single-perovskite energetic materials, such as (H2dabco)[Na(ClO4)3], (H2dabco)[K(ClO4)3], (H2dabco)[Rb(ClO4)3], (H2dabco)[Na(IO4)3], (H2dabco)[K(IO4)3] and (H2dabco)[Rb(IO4)3], all of them use alkali metal ions as an independent B component.If you believe that "Na + is formed as a whole with IO4 -as [I6NaO24] 5-", then none of the above substances can be regarded as perovskite energetic materials.Obviously, it isn't true.(4) Is a substance with a certain similarity in chemical composition to other substances not innovative enough in terms of its new structure?Energetic materials scientists should be aware that perchlorate-based perovskite materials are essentially double salts of two perchlorates.For example, (H2dabco)[Na(ClO4)3] is essentially composed of H2dabco(ClO4)2 and NaClO4.According to your logic, (H2dabco)[Na(ClO4)3] contains very similar components to H2dabco(ClO4)2 and NaClO4, so it does not exhibit a novel enough structure, and the perovskite energetic materials reported by Professor Xiaoming Chen are meaningless (Sci.China.Mater.2018,  61, 1123-1128).This is unlikely, also.
In response to your above question, we have made a detailed description on the novel structure I have carefully read the revised paper and the authors' response to the last submission and believe that this manuscript is not suitable for publication in Nature Communications for three main reasons:

Response:
We agree with part of your statement.
(1) Is it claimed in the revised manuscript that this perovskite material has the best ignition performance?In fact, we didn't suggest such an inappropriate description in the first revised manuscript.In the Abstract, it is stated that "Impressively, it affords ignition performance on par with the most powerful primary explosives reported to date", instead of "this perovskite material has the best ignition performance, ......, its performance does not surpass some existing primary explosives, such as copper azide and silver nitrotetrazolium".We sincerely hope that you can reconsider your comment and notice one of our important innovations, that is, discover the ignition performance of perovskite materials, and then make a positive evaluation of our research and efforts.( 2) Why does DPPE-1 have such excellent ignition performance?In the first revised manuscript, we explained that the ignition performance of DPPE-1 mainly depends on the strong oxidation ability of IO4 -.However, no detailed supporting information is given.Here, we calculate the heat of formation of DPPE-1, and evaluate the detonation performance of DPPE-1 by using program EXPLO 7.0 (see Table R1).The results show that its detonation velocity (D) and detonation pressure (P) are < 5500 m/s and <18.5GPa, respectively, which are lower than those of most primary explosives, indicating that the impressive initiation performance of DPPE-1 is hard to be well explained from the energy level.So, we turned our attention to oxidation capacity.According to the Tables of Standard Electrode Potentials (G.Milazzo et al 1978 J. Electrochem.Soc.125 261C), the standard electrode potential (E0) of IO4 -is 1.314V, while that of ClO4 -is 1.389V.Obviously, the oxidation of ClO4 -is stronger than that of IO4 -, which shows that the good initiation performance of DPPE-1 may be related to some unknown influencing factors besides the strong oxidation of IO4 -.We think that molecular stability is likely to play a crucial role, so we compare the Gibbs Free Energy (ΔG) of (H2dabco)2[Na(NH4)(IO4)6]n and (H2dabco)2[Na(NH4) (ClO4)6]n (see Table R2).The results show that the ΔG of (H2dabco)2[Na(NH4)(IO4)6] (ΔG = -144.95kcal/mol) is higher than that of (H2dabco)2[Na(NH4)(ClO4)6] (ΔG = -201.98kcal/mol), that is, the ClO4 -in (H2dabco)2[Na(NH4)(ClO4)6] has a good stabilizing effect, while the material based on IO4 -is relatively unstable, which may help us to understand the high mechanical sensitivity and strong initiation performance of DPPE-1.Such in-depth understanding is inseparable from the continuous support of reviewers, and we are very grateful for your kindness and patience.(3) Can IO4 -be used to build a primary explosive?When scientists are engaged in research, it is crucial to clarify the historical reasons behind it.The rise of green primary explosives stems from the the elimination of heavy metal biotoxicity from solid explosive products (e.g., Pb) of lead-based primary explosives.
Comment 2: "Ignition performance: The authors claim that this perovskite material has the best ignition performance, but as reviewer 2 said, its performance does not surpass some existing primary explosives, such as copper azide and silver nitrotetrazolium, so the authors' claim of the best performance is not appropriate.I also agree with reviewer 1 that the mechanism of such excellent ignition performance is lacking, although in the response that it was claimed to be caused by the high oxidation of IO4 -, but this is not enough.It is almost common sense that the XO4 -series ions can be used to construct primary explosives in the field of explosives.And now, XO4 -is not suggested to build explosives, because these halogens are inherently more toxic, which is contrary to the authors' proposed non-toxic design ideas (Scheme 1)." Although the perchlorate-based primary explosives developed in recent years have reduced toxicity to some extent, its gaseous explosive product (e.g.HCl) is still uncomfortable.Therefore, we need to understand that the toxicity of products is the fundamental driving force to promote the development of green primary explosives.This is common sense known to the experts of primary explosives.Although IO4 -has biological toxicity as the reviewer said, the main solid product of periodate-based primary explosives (I2, the confirmation of iodine in the product is shown in Figure R1 and Table R3) is a typical substance with sterilization and disinfection functions.R3).To confirm the I2 in the detonation product, (a) we filled the DPPE-1 in a pressure-resistant glass bottle and heated it in an oven to 200 ℃ As a result, we heard a huge explosion and the bottle was completely broken (Figure R1a-b); (b) we filled DPPE-1 in a Teflon reactor and heated it in an oven to 200 ℃.As a result, no explosion was heard and the detonation product stained the inner wall of the container purple, indicating the possible formation of I2 (Figure R1c-d).Further tests showed that the aqueous solution of the purple substance was yellow and immediately formed a blue solution after mixing with starch (Figure R1e-g), confirming the presence of iodine.The content of I2 based on the color comparison method is > 50%, which is consistent with the theoretical calculation.According to the above analysis, it is reasonable to think that IO4 -is preferred to ClO4 -to build primary explosives.
In response to your above question, we made a detailed explanation in the revised manuscript (See page 7, lines 24-33 and page 8, lines 1-44).The above calculation was completed using the EXPLO7.0program Table R2.The standard electrode potential and Gibbs free energy.

Response to Reviewer #3
Response: We cannot agree with your above statement.(1) The statement that "in my opinion, some conclusions are suspicious" is not appropriate.We believe that making such comments should not be based on subjective speculation, but on solid experimental data.The synthetic method is very simple, and all the raw materials are commercially available, which makes it very easy for you to verify the present results.We would appreciate it if you could reproduce our results.We also believe this will help you make accurate judgments, just as Reviewer #2 did (Comment 3).
(2) The statement that "some very close analogues of energetic perovskite class have been reported in refs.24, 37, 41, and 45-49" doesn't hold water.We think that above view is a crucial factor for you to make the conclusion that "the novelties of DPPE-1 is not high enough for publication on Nature Communication".In our view, such a judgment is not rigorous.The DPPE-1 reported in our manuscript shows a double-perovskite structure, while other substances reported in refs.24, 37, 41, and 45-49 show single-perovskite structure, which undoubtedly proves that DPPE-1 is different from known energetic perovskites.Although they share some components, it would be a mistake to classify them as very close analogues.In addition, growth in numbers usually implies new variations, possibilities, and functions.For single perovskites, there are theoretically N 3 (N = 1,2,3,......n) molecular combinations, while for double perovskite, the number may be extended to N 4 (N = 1,2,3,......n).Obviously, double-perovskite energetic materials have more possibilities.What reason do we have to think that its structure is not novel enough?Why isn't the increase in possibilities caused by structural changes an innovation?To take a similar example, it is well known that graphite, diamond, fullerene, graphene, carbon nanotubes and so on have exactly the same composition (C), but scientists did not believe that these new species were not an innovation.The main reason is that the slight changes in structure have led to many important discoveries, among which the discovery of fullerene and graphene has been awarded the Nobel Prize.The same principle applies to energetic perovskite.
Additionally, all known perovskite materials have no ignition function, while DPPE-1 has been proved to have excellent ignition performance.Isn't this innovation sufficient enough?To take a similar example, many new functions of the perovskite CH3NH3PbX3 have been discovered by scientists in recent years.However, the complete consistency in chemical composition does not deny the innovation of these works, nor does it reject their publication in Nature and Science.
In response to your above question, we made a detailed description in the revised manuscript (See page 4 lines, 11-21 and page 7, lines 13-20).We sincerely hope that reviewer can reunderstand our innovations in structural construction and performance discovery.

Comment 1: "In this manuscript, Feng et al. claimed that they find a new energetic double perovskite (named DPPE-1
) could be a promising primary explosive.In particular, they reported a very low minimum primary charge (MPC) of 5 mg for DPPE-1.The present findings seems very impressive, but in my opinion, some conclusions are suspicious.Moreover, in considering that some very close analogues of energetic perovskite class have been reported in refs.24, 37, 41, and 45-49, the novelties of DPPE-1 (neither in structure nor the usage as primary explosive) is not high enough for publication on Nature Communication." Response: Thank you very much for your detailed comments on our research, especially pointing out some serious errors in the manuscript, e.g., single crystal structure and elemental analysis, which we think will help improve the quality of our manuscript.
Crystal structure.The result of the initial refinement shows that DPPE-1 crystallized in the orthorhombic space group Pcab.However, it took us a long time to find out that this is in conflict with its obvious cubic system, and no energetic perovskites with Pcab space group have yet been reported (Table R4).Therefore, the crystal structure of DPPE-1 was refined for a second time, and it was finally identified as belonging to the cubic space group Pa-3.Unfortunately, this change was not corrected in time in the Supplementary Information, resulting in contradictory data.In response to this error, we have corrected it in the revised supporting document (see Table S1 lines 5-6).According to your request, we also uploaded the related refinement files, including completed cif files embedding HKL reflections and refinement details for fully checkcif (see DPPE-1 -2nd refinement.cif/.fcf/.hkl).I think these documents will enable you to make a positive evaluation of our work.
Elemental analysis.Data errors in elemental analysis were identified as the result of instruments not being calibrated for a long time.After careful calibration, we redetermined the elemental composition of DPPE-1 (see Table S5), and the results showed that the contents of C, H and N were 10.14%, 2.19% and 4.89%, respectively.We have addressed this issue and you can see the corrected data on page 10, line 29 in the revised manuscript and on page S2 in the revised supplementary information.
Table R4.Crystal system and space group of some reported energetic perovskites.
From the nitrogen content of DPPE-1 (uncalibrated), the reported substance seems more likely to be a DAI-4-based mixture or solid solution.However, we also note that neither case explains why the contents of carbon and hydrogen of DPPE-1 (uncalibrated) are much higher than those of any substance listed in Table R5, including DAI-X1, DAI-1, and DAI-4.The most likely reason is that the data listed in the manuscript is wrong.Subsequently, we calibrated the instrument and remeasured the element composition (Table R6).The results show that the measured data Comment 3: "Page 9, line 2, "EA calculated for C12H32I6N5NaO24 (1414.82g mol -1 ): C 10.19, H 2.28, N 4.95; Found: C 10.30, H 2.69, N 5.83."The experiment wt% value (5.83) for N element is significantly higher than the expected one (4.(DPPE-1 (calibrated)) are highly consistent with the theoretical calculation (DPPE-1 (calculated)).Therefore, the substance we reported is not DAI-4 but DPPE-1.We have addressed this issue and you can see the corrected data on page 10, line 29 in the revised manuscript and on page S2 in the revised supplementary information.The single-crystal X-ray diffraction is considered to be the "Gold Standard" for structural determination.The crystal structure in the manuscript clearly confirms that the reported substance is DPPE-1 rather than DAI-4.Furthermore, if DPPE-1 cannot be prepared as reliably as DAI-4, this means that the acquisition of DPPE-1 is a low-probability event.If this is true, it would not explain why we always get DPPE-1 instead of DAI-4 or some other substance in the process of randomly selecting crystals for structural determination.Combined with the crystal structure, nuclear magnetic resonance and the calibrated elemental composition, we were able to conclusively confirm that the target substance was DPPE-1.In response to your above question, we have made a detailed supplementary explanation on the structure of DPPE-1 in the revised manuscript (See page 4, lines 7-11 and 19-21).

95). As disclosed in the ref. 41, NH4+ could easily assemble into (H2dabco)(NH4)(IO4)3 (named DAI-4) with 75% yield, whereas sodium ion is relatively smaller for directly constructing (H2dabco)[Na(IO4)3] (named DAI-1) from solution but giving (H2dabco)[Na(H4IO6)3] (DAI-X1) that could converted DAI-1 after dehydration at 80 °C. These facts in ref. 41, together with the mismatch in the present EA results, strongly imply that the sample used in the present manuscript is most-likely a mixture (main component should be DAI-4 with 5.96 wt% of N element, rather than the ideal DPPE-1 with 4.95 wt% of N element) or a solid solution (i.e., a larger amount of sodium sites are replaced by NH4+ in the ideal DPPE-1) but not the declared pure DPPE-1. Regardless of the situations, it means that the obtained sample is more close to the known DAI-4, or the ideal DPPE-1 cannot be prepared as reliably as DAI-4, bringing troubles to subsequent applications. As all these relevant compounds have very close simulated PXRD patterns, the identify for the present sample should be very carefully (a pawley refinement maybe helpful in a certain degree)."
Response: Thank you very much for your detailed comments on our work.However, the suggestion "to study the potential as primary explosive for DAI-4" indicates that you may not understand the importance of our research.The reasons are as follows: (1) The innovations of this research are that it expands the number of energetic perovskites through a new structure (from N 3 of single perovskites to N 4 of double perovskites, N=1,2,3,.....n) and discovers a new function of energetic perovskites, namely ignition performance.Energetic materials experts would be able to take note of these two points and immediately realize the great value of our research.Here, the purpose of MPC test is to confirm the desired ignition performance, it is not necessary to make a detailed analysis of various factors that affect MPC, such as purity, form, quality, size, and morphology.This is a protracted work; (2) It is well known that there is a considerable time span (ranging from a few years to a dozen years) from basic research, applied research, engineering technology to the final product.In this sense, it is highly impractical to try to solve all the issues related to DPPE-1 in a single research paper.Generally, the practical charge is considered in the process of initiating explosive devices development (depending on the application environment and product type), while what we are doing now is basic research that serves as an inspiration to other scientists and engineers.In other words, it is meaningless to discuss the practical charge of DPPE-1 in this paper; (3) The MPC of primary explosives is determined according to a predetermined standard, such as GJB5891-2006 adopted by scientists in China.In this standard, there are no requirements on the purity, crystalline form, crystal quality, crystal size and morphology of the sample.With the exception of K2DNAT, the MPCs of the other primary explosives (e.g.DDNP, ICM-103, ANTPA, LA) were measured without taking into account the above influencing factors.(4) Considering that DPPE-1 is more novel than DAI-4 in both structure and performance, and that the misinterpretation raised about the structure of DPPE-1 have been proved to be incorrect, we do not accept your proposal to study DAI-4.

Response:
The language, novelty and importance of the manuscript have been evaluated and polished by professional institutions.Even so, we will try our best to improve our writing.
Comment 4: "For MPC test, the present lead-plate experiment is relatively preliminary.There are many factors highly affect MPC, such as the sample purity, crystalline form, crystal quality, crystal size and morphology.Therefore the reported MPC in different literature usually fluctuate within a certain range.In addition, the practical primary charge is not only determined by MIC, but also closely related to the detonation reliability under different conditions.For instance, different from the MPC of 30 mg for well-known LA reported in ref. 10, the MPC of 7 mg for LA is usually found in some textbooks, and the practical primary charge of 30 mg LA is usually needed in order to achieve stable detonation every time.Moreover, in order to compare the initiation ability of different initiating explosives, comparative experiments should be conducted under the same conditions.In addition, in considering that the present DPPE-1 sample may be a mixture or solid solution which do not easily and reliably prepared, I strongly suggest the author to study the potential as primary explosive for DAI-4."Comment 5: "The writing is not good and rigorous.Many author names are wrong in reference lists."Finally, we hope that you will appreciate the two important innovations involved in this study and make very positive comments accordingly.
Response: This is the most valuable academic communication I think.Up to now, we have synthesized at least 50 energetic perovskite materials.In the next two years, the number of perovskite energetic materials in our laboratory will be increased more rapidly in order to provide the basis for screening primary explosives with better comprehensive properties.According to our available studies, halogens seem to play a decisive role in the initiation performance of energetic perovskites.For example, compared with ClO4 --based materials, IO4 --based materials are more likely to exhibit high sensitivity, rapid exothermic processes, and strong initiation performance, while BrO4 --based materials are too unstable to be synthesized and used as energetic materials.
In the first revised manuscript, we explained that the ignition performance of DPPE-1 mainly depends on the strong oxidation ability of IO4 -.However, such an oversimplified explanation does not satisfy the reviewers.Here, we calculated the heat of formation of DPPE-1, and evaluated the detonation performance of DPPE-1 by using program EXPLO 7.0 (see Table R7).The results show that its detonation velocity (D) and detonation pressure (P) are < 5500 m/s and <18.5GPa, respectively, which are lower than those of most primary explosives, indicating that the impressive initiation performance of DPPE-1 is hard to be well explained from the energy level.So, we turned our attention to oxidation capacity.According to the Tables of Standard Electrode Potentials (G.Milazzo et al 1978 J. Electrochem.Soc.125 261C), the standard electrode potential (E0) of IO4 -is 1.314V, while that of ClO4 -is 1.389V.Obviously, the oxidation of ClO4 -is stronger than that of IO4 -, which shows that the good initiation performance of DPPE-1 may be related to some unknown influencing factors besides the strong oxidation of IO4 -.We think that molecular stability plays a crucial role, so we compare the Gibbs Free Energy (ΔG) of (H2dabco)2[Na(NH4)(IO4)6]n and (H2dabco)2[Na(NH4) (ClO4)6]n (see Table R8).The results show that the ΔG of (H2dabco)2 [Na(NH4)(IO4)6] (ΔG = -144.95kcal/mol) is higher than that of (H2dabco)2[Na(NH4)(ClO4)6] (ΔG = -201.98kcal/mol), that is, the ClO4 -in (H2dabco)2[Na (NH4)(ClO4)6] has a good stabilizing effect, while the material based on IO4 -is relatively unstable, which may help us to understand the high mechanical sensitivity and strong initiation performance of DPPE-1.Such in-depth understanding is inseparable from the continuous support of reviewers, and we are very grateful for your kindness and patience.
In response to your above question, we have made a detailed supplementary explanation on the role of halogen towards the energetic properties in the revised manuscript (See page 7, lines 27-33 and page 8, lines 1-16).

Response to Reviewer #1
Response: The reviewer has discussed the issue of structural novelty with us for three times.The earliest one occurred when the manuscript was submitted to Nature (see Figure R1).Up to now, we are still confused as to why the reviewer has consistently denied the significant structural differences between energetic single perovskites and energetic double perovskites.The similarity in composition cannot stifle innovation in structure.Nevertheless, we still appreciate the efforts made by the reviewer to improve the quality of our manuscript.In addition, we have cited all relevant references mentioned by the reviewer (as shown above) in our previous manuscript and conducted a detailed examination of the relevant references.However, as of the time we submitted to Nature and Nature Communications, we did not find any reports on energetic double-perovskite structures and perovskite primary explosives.As shown in Figure R2, the latest study on perovskite primary explosives was submitted to Small on March 2, 2023, which was later than our earliest submission to Nature on December 27, 2022.Clearly, we launched our research earlier.
It is even more noteworthy that: (1) DPPE-1, as reported by us, is still the only energetic double perovskite to date; (2) The synthesis method we reported is carried out at room temperature, and the raw materials used are relatively safe inorganic salts.On the contrary, the synthesis of single-Comment: After carefully reading the comments of the other two reviewers as well as the authors' responses, I agree with the third reviewer's viewpoint and still think that this paper is not suitable for publication in Nature Communications, and its main problem is that the structure presented in this paper is really too similar with the compounds reported.I have to cite the relevant literatures once again to support my viewpoint.In addition to the very similar structure, its potential application as primary explosive has also been scrutinized, see literature "Small 2023, 2302631, DOI: 10.1002/smll.202302631".In my opinion, this published Small paper is superior to the submitted manuscript, in terms of the structural diversity, experimental integrity and mechanistic explorations.It can also be found that the structures and compositions of these materials are very similar, all employing H 2 DABCO and IO 4 -, further suggesting that the structure in this manuscript is not novel.perovskite energetic materials reported in the paper published in Small needs to be carried out under higher temperature (65℃) and strong oxidizing acid (H 5 IO 6 ), which is uneconomical and dangerous.As shown in Figure R3.(3) The TDPIs series of substances reported in the paper published in Small still lag behind DPPE-1 in terms of initiation capacity (5mg of DPPE-1 vs 10mg of TDPI-1), which actually proves that the ignition performance of double-perovskite energetic materials is better than that of single perovskite energetic materials.In other words, TDPIs highlight the significant advantages of DPPE-1, rather than "this published Small paper is superior to the submitted manuscript".Once again, we thank you for your great efforts in reviewing this manuscript.

Response to Reviewer #2
Response: We really appreciate your positive comments on our research.At the same time, we thank you for your great efforts to review and improve the quality of this manuscript.
Comment: Wow, this is an impressive Letter to Reviewer.The authors put a lot of efforts in further improving this manuscript and to explaine the curiosity of this class of compounds.Th aks for deleting the MPC.O hope this significant work will be published soon in Nature Comm.

Response to Reviewer #3
Response: We have carefully checked the references related to perovskite energetic materials..However, as of the time we submitted to Nature and Nature Communications, we did not find any reports on energetic double-perovskite structures and perovskite primary explosives.
As we replied to the reviewer #1, (1) the latest study on perovskite primary explosives was submitted to Small on March 2, 2023, which was later than our earliest submission to Nature on December 27, 2022.Clearly, we launched our research earlier.(2) DPPE-1, as reported by us, is still the only energetic double perovskite to date; (3) The synthesis method we reported is carried out at room temperature, and the raw materials used are relatively safe inorganic salts.On the contrary, the synthesis of single-perovskite energetic materials reported in the paper published in Small needs to be carried out under higher temperature (65℃) and strong oxidizing acid (H 5 IO 6 ), which is uneconomical and dangerous.As shown in Figure R3.(4) The TDPIs series of substances reported in the paper published in Small still lag behind DPPE-1 in terms of initiation capacity (5mg of DPPE-1 vs 10mg of TDPI-1), which actually proves that the ignition performance of doubleperovskite energetic materials is better than that of single perovskite energetic materials.
Comment: I agree the most of the responses from the authors, including those concerning the wrong EA results and the structure refinement.However, I am afraid that two main novelties of DPPE-1, an idea from a single perovskite energetic crystal to a double perovskite energetic crystal and an application using DPPE-1 as primary explosive, are still not insufficient to be published on Nat.Commun.In particular, recently I found out that a very similar work using periodate-based perovskite energetic materials (i.e., DAI-1/2/3/4 reported in ref. 42 by a group from Sun Yat-Sen university) to be primary explosives was reported in Small (2023, DOI: 10.1002/smll.202302631) by a group from Nanjing University of Science and Technology..

1 A
Point by Point Response to the Reviewer´s Comments

Figure R2 .
Figure R2.Order for professional evaluation.

Figure R1 .
Figure R1.Record of submission to Nature.

Figure R2 .
Figure R2.Record of submission to Small.

Table R3 .
The Thank you very much for your positive comments on our work.As you said, "the thermal decomposition temperature of DPPE-1 is not outstanding", but "It is true that the current thermal stability has indeed reached the basic requirements for practical applications".In fact, we are currently trying to develop a new periodate-based perovskite primary explosive with the purpose of "......search for perovskite-type green primary explosives with thermal decomposition temperatures higher than 200 ℃ or even 250 ℃" that we mentioned in the conclusion.It is of great academic and commercial value to achieve this goal, as I have done with ICM-103 research (Nat.Commun.The referee provided us with positive comments on our manuscript, e.g., "Congratulations again to the outstanding and impressive new perowskite compound" and "...... totally recommend publication of this manuscript in the present journal".particlesizescreening and ignition performance test, and (2) the data of test pressure and grain size of the other four initiating substances are missing, we decided to delete line MPC in Table1to avoid trouble caused by using different setups and secondary explosives (PETN and RDX)."Congratulations again to the outstanding and impressive new perowskite compound.It is really simple and could be of potential use.I totally recommend publication of this manuscript in the present journal.Some of the overdrawn formulations have been changed from the previous version.This is gratefully acknowledged."Comment 2: "I still have a strong problem with table 1 line mpc.The values given here for the other compounds are simply not correct.All of the references given here are not determining the detonation product of DPPE-1 calculated based on the EXPLO 7 program., 2019, 10, 1339, four professional institutions have jointly carried out commercial application).In any case, DPPE-1 reported in this manuscript is of great significance for promoting the development of a perovskite primary explosive, which is what we are pursuing.We hope that you will appreciate our work.In response to your above question, we made a brief description in the revised manuscript (See page 5, lines 42-44 and page 6, line 1).Comment 3: "Thermal stability: The thermal decomposition temperature of DPPE-1 is not outstanding, although it has similar thermal stability with the famous DDNP.But with the increasing safety requirements in the field of explosives, it was required that the thermal decomposition temperature of explosives should reach 180 degree.It is true that the current thermal stability has indeed reached the basic requirements for practical applications, but 161.3 degree is really not sufficient."ResponsetoReviewer#2Conclusion:Response:Wereallyappreciatethe reviewer's conclusion that "this work should be published and is of great interest to other researchers in high energy materials research".In addition, we thank the reviewer for pointing out our carelessness.According to the reviewer's suggestion, the line MPC in Table1has been deleted in the second revised manuscript (see Table1).Upon careful examination, we found that the charge mass (50 mg) of K2DNAT reported in the cited literature (Angew.Chem.Int.Ed.2015, 54, 10299-10302) may not be the minimum primary charge (MPC).Considering that (1) K2DNAT is extremely sensitive, and the detonation velocity and pressure are as high as 10011m/s and 52.2GPa respectively, it is extremely dangerous to carry out synthesis, mpc, they only give examples or amounts of a specific detonator setup.Soeither you have to determine the mpc of the other compounds in your setup, with all desired values such as pressure, grain size etc. or this line should be deleted.At least the values of the compared explosives must be deleted.I do not want to say your perowskite is bad and lower than others but the authors should know that one cannot compare reference data using different setups and PETN and RDX charges for comparison.In out preliminary tests we acchived a similar initiation capability to LA which is quite nice.To summarize, this work should be published and is of great interest to other researchers in high energy materials research" Comment 3: "We have checked the synthesis, which worked quite fine.The analytic data largely fit to our observations.Our DTA was a bit lower for example.The methodologies used by the authors are appropriate and meet the desired standards.Good luck for the future.I know there are other Chinese research groups working on the exact same class of compounds."

Table R5 .
Elements and contents of several perovskite materials.

Table R7 .
Detonation performance of DPPE-1."Iwouldlike to know the role of Halogen towards the energetic properties in this compound."detonationproductsarenon-toxicandlowtoxic(see TableR9), and the main solid product I2 has bactericidal and disinfection function, which makes it a possible promising energetic biocidal agent (see FigureR3.Sci China Mater., 2023, 66, 1641-1648).To sum up, DPPE-1 satisfy the green energetic materials criteria.In the revised manuscript, we explain this in detail (See page 8, lines 17-44).

Table R9 .
The detonation products of DPPE-1 calculated based on the EXPLO 7 program.